Broadcasting transmits a packet that will be received by every device on the network. The broadcast is limited to a broadcast domain:
Broadcast
Unicasting specifies one-to-one transmission from one point to another point in the network:
Unicast
A free e-book, Brocade IP Primer, is a very good resource and can be found at https://community.brocade.com/t5/Ethernet-Switches-Routers/Brocade-IP-Primer-eBook-Download-Now/ta-p/2905.
Multicasting specifies one-to-many where data transmission is addressed to a group or destination:
Multicast